NEW YORK — Drivers have long known that slowing down on the highway means getting more miles to the gallon. Now airlines are trying it, too — adding a few minutes to flights to save millions on fuel.

Southwest Airlines started flying slower about two months ago, and projects it will save $42 million in fuel this year by extending each flight by one to three minutes.

On one Northwest Airlines flight from Paris to Minneapolis earlier this week alone, flying slower saved 162 gallons of fuel, saving the airline $535. It added eight minutes to the flight, extending it to eight hours, 58 minutes. That meant flying at an average speed of 532 mph, down from the usual 542 mph.

Fliers, already beleaguered by higher fares, more delays and long security lines, may not even notice the extra minutes. The extra flight time is added to published flight schedules or absorbed into the extra time already built into schedules for taxiing and traffic delays.

— From wire reports